Only first slide is rendered
@DiegoAdum the problem is in the composting , you are combining a layer from blender_internal and a layer from Cycles ,you'll have to render the Volumetric scene first , or remove the composting and render both than pass the images through the processing.

Thanks @Chebhou!! Following your suggestion I change the scene and press Animation button. the render start but only for the 2 scene. I change back the scene to the first one and hit Animation button and now is working again! It seems something was blocked!!! Thanks a lot!!!